To provide a good service to your customers, your external endpoint should be served through HTTPS. This means that the communication between you and your customers is private, and it can't be sniffed throughout the network route.
The way HTTPS works is that the server and client encrypt the communication. To be sure that the server is who they say they are, there needs to be an SSL certificate issued by an authority that grants that the DNS is verified.
Remember, the point of HTTPS is not that the server is inherently trustworthy, but that the communication is private between the client and the server. The server can still be malicious. That's why verifying that a particular DNS does not contain ...
